The presently disclosed subject matter relates to an apparatus for analyzing an electrocardiogram acquired from a subject.
Usually, ventricular tachycardia means a condition where the heartbeat is different from the normal rhythm of the heart, and premature ventricular contraction occurs frequently in the ventricle. Ventricular tachycardia may cause worsening of heart failure, and sudden death, and therefore requires attention.
Conventionally, therefore, it is known that ventricular tachycardia is treated by selectively performing ablation on the abnormal site which causes ventricular tachycardia, by using a cardiac catheter. In order to perform the treatment, it is important to correctly identify the position where ablation is to be performed.
With respect to identification of the position of an abnormal site in the ventricle, it has been reported that, in a myocardium portion of the ventricle in which a substrate for ventricular tachycardia exists, high-frequency LAVA (Local Abnormal Ventricular Activities) are observed in addition to a sinus rhythm ventricular wave (V-wave). There is a non-patent Literature 1, Bieito Campos et al., “Use of Novel Fragmentation Map to Identify the Substrate for Ventricular Tachycardia in Post Infarction Cardiomyopathy,” Heart Rhythm, 2014 October. The non-patent Literature 1 proposes an analysis technique in which a frequency analysis is performed on an intracardiac electrocardiogram of the ventricle, thereby quantitatively analyzing a ratio of LAVA contained in a sinus rhythm ventricular wave.
In an intracardiac electrocardiogram of the ventricle, however, LAVA sometimes appear after a sinus rhythm ventricular wave, and in other cases appears overlappingly with a ventricular wave. Moreover, an intracardiac electrocardiogram may contain noises due to the contact state of an electrode of a catheter, those caused by influences of myocardial sites which are remote from the measurement site (an atrial wave and a far-field potential), etc. In the case where a frequency analysis is to be performed on an intracardiac electrocardiogram of the ventricle as disclosed in Non-patent Literature 1, therefore, a medical person must adequately adjust and set an analysis time range of the frequency analysis while the shape of each unit waveform contained in the intracardiac electrocardiogram, and waveforms before and after the unit waveform are checked so that LAVA do not leak from the analysis time range. In the technique, in the case where points (mapping points) from which an electrocardiogram is to be acquired are as many as several hundreds, a process of setting the analysis time range takes a long time. Therefore, it is difficult to, during catheter treatment, identify the position of the abnormal site by a frequency analysis.
Therefore, it is an object of the presently disclosed subject matter to provide an electrocardiogram analyzer in which a frequency analysis can be performed on an intracardiac electrocardiogram of a ventricle in a manner easier than the conventional technique.